Display shows E4 and the Klarstein coffee maker with grinder will not grind or brew.

Safety first: Unplug the coffee maker before working near the grinder. Keep fingers away from the burrs.

Clear a grinder jam:

• Remove the bean hopper and empty all beans.
• Use a flashlight to inspect the grinder inlet for stones, hard objects, or oily clumps of coffee.
• Gently turn the grinder burr by hand (if accessible) to free any stuck beans. Do not use metal tools that can damage the burrs.
• Vacuum out loose grounds using a small nozzle; avoid blowing compressed air into the grinder as it can push debris deeper.
• Reinstall the hopper and add a small amount of fresh, dry beans. Avoid very oily dark roasts which can cause sticking.

Reset and test:

• Leave the machine unplugged for 10 minutes to allow the grinder motor thermal protector to reset.
• Plug back in and run a grind-only or small-cup cycle to test.

If E4 returns immediately, the grinder motor or its driver circuit may be defective and require replacement.